How does the width of the QRS complex differ between SVT with wide QRS and V-tach?

How does the width of the QRS complex differ between SVT with wide QRS and V-tach?

• A. SVT: greater than .14 seconds, V-tach: less than .14 seconds
• B. SVT: less than .14 seconds, V-tach: greater than .14 seconds
• C. Both SVT and V-tach: less than .14 seconds
• D. Both SVT and V-tach: greater than .14 seconds

Answer: (B)

The width of the QRS complex is a crucial factor in differentiating between supraventricular tachycardia (SVT) with a wide QRS and ventricular tachycardia (V-tach). For SVT, particularly when its characteristics include a wide QRS, the QRS duration will typically be less than 0.14 seconds. This can occur when there is aberrant conduction, such as with a pre-existing bundle branch block affecting the conduction through the ventricles.

In contrast, V-tach is characterized by a broader QRS complex, generally exceeding 0.14 seconds. This extended duration is due to the fact that V-tach originates from the ventricles directly, leading to a slower and less coordinated activation of the ventricular myocardium.

Understanding these distinctions is essential for proper diagnosis. SVT with a wide QRS typically involves conduction abnormalities but retains the rapid rate associated with SVT, while V-tach represents a potentially more critical condition with its wider QRS complex reflecting a dysfunctional ventricular rhythm.